on this sunday night, state of play. a big change in the polls tonight while the president gets a post convention lift even he didn't see coming. and a surprise move from mitt romney, what he is saying now about the president's health care plan. wild weather blows through the east where tornadoes in new yo city. plus a new storm brewing in the tropics. fighting lung cancer. tonight what doctors are calling a promising new way to treat the deadly disease. out of the sky, the mystery surrounding part of a jumbo jet that came crashing into a neighborhood. and if it doesn't fit, you must acquit. remember that 17 years later the prosecutor in the o.j. trial

makes a stunning allegation about that infamous moment. from nbc news world head quarters in new york, this is "nbc nightly news" with lester holt. good evening. after weeks running virtually neck and neck a new poll shows some day light has suddenly opened up between president obama and mitt romney. the president making a bounce in florida where he tried to pivot the conversation away from high unemployment and on to an area that he hopes to prove to be governor romney's achilles heal. romney told our david gregory what part of the president's health care law he would like to keep in place. kristen welker joins us from west palm beach with more on all of that as well as what has to be the picture of the day.

>> reporter: good evening to you. we will get to that picture in a moment. the candidates over taxes and medicare as president obama opened up a lead in what has otherwise been a razor tight race. campaigning in florida today president obama tried to turn the focus to medicare. >> i want you to know, florida, i will never turn medicare into a voucher. >> reporter: the president is enjoying a post convention bump, the latest galup poll showing him up. romney disclosed he would preserve the most popular parts of the president's health care plan, something he said before but went into more detail today. >> i'm not getting rid of all health care reform. there are a number of things that i like that i will put in

place. >> reporter: romney said he would allow individuals to add policies to cover family members up to any age and the candidates sparred over taxes. when asked to name a loop hole he targeted romney replied. >> people at the high end, taxpayers will have fewer deductions. >> reporter: he gave no further specifics opening the door for president obama to take a swipe. >> that is not bold leadership. that's bad math. that gets a failing grade. >> reporter: ann romney also entered defending her husband after a barrage of attacks from the left. >> our life has always been devoted to those that are struggling more than we are. and i was grateful for the opportunity we had at the convention for others to speak up and talk about the kind of lives we have led in particular.

>> reporter: saturday night a little bit of fun on the trail when the birther issue came up again, this time inside a sports bar in orlando and brought up by the president himself. >> you have a birth certificate? >> yes, sir. >> reporter: and continued today when the president stopped by a florida pizza shop and the owner gave him an unexpected lift. back on the campaign trail this week in the big battleground states one more point former president bill clinton will be stopping here in florida. >> i have to ask you about that hug there in the pizza parlor. that was first seen as a still photo. people expressing surprise someone can get that physical with the president. what is the back story here? >> reporter: officials with the secret service won't go into a lot of detail except say people

touch the president all the time. that pizza shop owner asked if they were puturbed and they told him no as long as he didn't take the president away. he has been recognized for his blood donor organization. he voted for president obama in 2008 and plans to do so again this year. >> kristen welker, thank you. on the trail in florida. we want to bring in cnbc chief washington correspondent john harwood. the conventional wisdom has been that the economy was going to drive this election. is that still the case? >> it is still the case though not in the way it was earlier in the year. democrats work hard to turn this from a referendum on economic management to a choice between two visions. he has gotten a home made bounce firming up support with young

voters, women. >> do the debates become more critical for romney assuming this bounce lasts a little longer than he would like? >> no question about it. i talked to a senior republican strategist today who said it is hard to take out an incumbent president who is personally popular. the last chance for romney to do that will be in the debates in october. >> john harwood, thank you. another big story. the severe weather that struck the eastern seaboard this weekend including tornadoes here in new york city. we have a report from michelle franzen. >> reporter: up and down the east coast cleanup today after a series of violent storms. >> look at the tornado. >> reporter: that even spawned a pair of tornadoes in two new york city neighborhoods. the first twister formed over the atlantic before moving on to land ripping through a sea side community on the edge of queens. ten miles away a more powerful

tornado tore through a densely populated brooklyn neighborhood damaging several homes and downing trees. >> my son was looking at it out the window. he was like we are gelting hit by a tornado. >> reporter: homeowners are still assessing the damage in this neighbor but feel lucky that no one was injured. >> we have been fortunate nothing happened. >> reporter: the threatening skies caused delays at sporting events. in new jersey rutgers football fans ran for cover. washington was hit hard with winds of nearly 60 miles per hour. in virginia and maryland the storms toppled trees and left 150,000 customers without power. and on the potomac river 19 people were rescued after the racing boat they were on capsized. what powered these storms? >> we saw a shift in the weather pattern with cooler air dropping down and that produced 300 wind

reports all across the northeast and then we got the tornadoes in new york city on top of that. >> reporter: volatile storms that are not uncommon this time of year but this weekend they packed an extra punch. michelle franzen, nbc news, new york. we are following active storms in the atlantic tonight. tropical storm leslie has just passed by bermuda and will continue to cause high surf and rip tides. jim cantori is watching this storm from bermuda tonight. >> reporter: it has been a very rainy day. this area is about 12 inches down in rainfall. we just got word from the national security minister that he is giving bermuda the all-clear in terms of having no injuries and no major structural damage. leslie is still a big storm and will make its way to canada. this thing has about a 200-mile

wide tropical storm windfield. even though it missed us by 140 miles we were still within 60 miles of the tropical storm force winds. the path takes it to the north and east and on tuesday it could still become a minimal hurricane. folks in st. johns will probably see watches and warnings come out later on this evening. here we are almost at the exact peak date of the atlantic hurricane season and we have leslie, michael and the next disturbance. some of the long range computer models don't take the next disturbance anywhere near land. we are only half way through the season. we will see what else mother nature has in store as we head through the rest of september and october. in chicago tonight it is going down to the wire where teachers in the country's third largest school system are threatening to strike at midnight. kevin tibbles is in our chicago

bureau tonight following this developing story. >> reporter: tonight parents of children in the nation's third largest school district are holding their breath. chicago's 29,000 public school teachers and support staff are poised to strike tomorrow leesk over 400,000 kids with no instruction. the school board and teachers have been negotiating throughout the weekend. while both sides say they are getting closer, they are not there yet. with a midnight deadline pressure is mounting. salary and teacher evaluations are the hot button issues here. the teachers union is handing out picket signs and the city has arranged for some 140 schools to be open for half a day tomorrow to ensure kids who need it get breakfast and lunch. still many parents are concerned it won't be enough. a protracted teachers strike may

be the first real test for mayor emanual here. he pushed for an extended school day in helps of improving a lagging graduation rate. overseas today was one of the deadliest days in iraq since u.s. combat forces left the country. officials say at least 90 people were killed and hundreds more wounded in dozens of bombings and shootings. in syria at least 17 people were killed when a car bomb exploded in aleppo. ann curry made her way into syria. look for her reporting this week. some important health news about lung cancer. a large new study on the genetic makeup of one type of lung cancer is raising hopes that new treatments may soon be available for this killer.

robert bezel is live with more. >> the study looked at one type of lung cancer that accounts for about one in four cases of the disease. as part of a giant government funded research project scientists sequenced all the jeangen genes in 178 patients. several of the drugs that may work are already on the market or in late testing phases. researchers say based on this new information clinical trials will begin soon to find out how many new treatments this treasure-trove of genetic information will bring. still ahead as we continue here on "nbc nightly news" the mystery surrounding part of a jumbo jet about the size of a refrigerator that came falling

from the sky crashing into a neighborhood. the allegations about o.j. simpson's star attorney and those infamous gloves. nearly everything in it?mad gave it greater horsepower and best in class 38 mpg highway... ...advanced headlights... ...and zero gravity seats? yeah, that would be cool. ♪ introducing the completely reimagined nissan altima. it's our most innovative altima ever. nissan. innovation that excites. ♪ try the #1 gastroenterologist recommended probiotic. align. align naturally helps maintain digestive balance. ♪ ooh, baby, can i do for you today? ♪ try align today.

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hadlock. >> reporter: it is a mystery of sorts. >> and this big part landed behind that red car over there. >> reporter: how a landing gear door from a passing jetliner ended up crashing into a seattle area neighborhood. >> it was a big flap of metal. >> reporter: neighbors say they saw a low flying plane just before the door slammed to the ground. >> i came back and there was a part of an airplane sitting here. >> reporter: a tag on the door indicates it came from a boeing 767. >> they are going to look at the maintenance of it and then also whether the airplane, whether the gear was extended at the proper speeds. >> reporter: it is not the first time airplane parts have rained down. last may in toronto chunks of metal from an engine peppered a neighborhood with debris

smashing car windows. in florida the door from a stairwell ripped away and landed on a golf course. in 2009 an engine exploded on takeoff in brazil. the plane landed safely but bum barded a neighborhood with parts. >> when you think of the amount of flights we do per day both with the airline airplanes as well as general aviation there are thousands of airplanes that fly every day and it is very rare to have something come off of them. >> reporter: back in washington state john hanson is holding on to part of a plane's door. >> a souvenir. >> reporter: charles hadlock, nbc news. we are back in a moment with a new twist tonight in the o.j. simpson trial. and what that feels like. copd includes chronic bronchitis and emphysema. spiriva helps control my copd symptoms by keeping my airways open a full 24 hours.

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what a spectacular summerer it has been for the brits, the queen's jubilee and the olympics and the closing ceremony at the paralympics. now to the new twist in the o.j. simpson case. 17 years after the so-called trial of the century one of the prosecutors is having serious allegations claiming cochran and the defense team tampered with with evidence. we get our report tonight. >> reporter: it is one of the most memorable images o.j.

simpson struggling to put on a pair of bloody gloves that prosecutors say he was wearing at the time. >> he could not get his hands in them leading his attorney to utter these now infamous words. >> if it doesn't fit, you must acquit. >> reporter: nearly 17 years later simpson is in prison on kidnapping and robbery charges. cochran passed away in 2005. and prosecutor is now claiming there is a reason the gloves did not fit. >> what i think happened is that the glove was manipulated so it did not appear to look as if it fit. >> reporter: during a panel last week defense attorney claimed johnny cochran was the culprit. >> i think johnny tore the

lining so that o.j.'s fingers could not go under the glove. >> he is still making excuss. >> reporter: a member of simpson's defense team says darden is lying. what he says happened was impossible. >> the glove was never in the possession of the defense unsupervised until after the glove was tried on. >> reporter: darden declined the request for comment. while the claims would never be proven what he did prove is that the trial of the century still has the power to captivate our attention. the pain at the pumpkins across much of the country tonight. aaa says the average price of a gallon of gas jumped another 8 cents now $3.83 a gallon. aaa says it expects the price to drop. refineries are switching to the less expensive winter blend

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>> reporter: lauren shield is wise beyond her 12 years. >> i know a lot of medical terms and a lot of stuff that a lot of 12 year olds wouldn't know because i have gone through a lot. >> reporter: that is putting it mildly. four years ago a virus caused her heart to fail. >> they put her on cardiac and respiratory life support. >> reporter: lauren got a heart transplant. her mother recalls the moment her daughter woke up. >> it is a day where we can finally start to think about going home. >> reporter: it is emotional. >> absolutely. i can go right back to all of those moments very quickly. >> reporter: now lauren wants to take what she calls her good fortune in getting a heart and pay it forward. >> reporter: how lucky do you feel? >> extremely. there is a reason why i got my heart.

it is to spread the word on organ donation. >> reporter: right now new york state ranks second to last in organ donations in this country, very unsettling news to more than 10,000 people in this state currently waiting for a transplant. >> we found that 97% of people do it through department of motor vehicles. >> reporter: so the shields teamed up with new york state senator and in june the state legislature passed lauren's law. >> say yes to saving lives and join us. >> reporter: tell me what lauren's law is. >> when you go to the dmv or renew your license the donor question on the form is mandatory to answer. >> reporter: for the first time you have to answer the question either yes i'd like to be an organ donor or skip this question. >> we have seen other states with a higher rate. they simply ask the question.

>> reporter: new york governor is expected to sign the bill into law this month. >> even one life would make it all worth it. >> basically you are giving the gift of life and it is the best gift to give. that's "nbc nightly news" for this sunday. coming up next football night in america followed by sunday night football, the steelers versus the broncos. brian williams will be here tomorrow. i'm lester holt reporting from new york. from all of us here at nbc news, good night. -- captions by vitac -- www.vitac.com